Aqueous resistant metal pigment-containing paste and method for making

ABSTRACT

Metal pigment particles which are treated with a heteropolyanion compound, a phosphosilicate compound or a combination of a heterpolyanion compound and a phosphosilicate compound show increased stability against attack by water. The particles are especially useful in aqueous coating compositions.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of Ser. Nos. 08/104,548, filedAug. 11, 1993, 08/104,550, filed Aug. 11, 1993, and 08/136,286 filedOct. 15, 1993, now U.S. Pat. Nos. 5,296,032, 5,348,579 and 5,356,469respectively.

FIELD OF THE INVENTION

The present invention is related to paste compositions containing metalpigment particles suitable for forming coating compositions,particularly aqueous coating systems. Increasingly stringentenvironmental regulations have required that coating systemsdramatically reduce volatile organic solvent levels. One way to complywith such regulations is to use water in place of the volatile organicsolvents previously used.

BACKGROUND OF THE INVENTION

Within this application several publications are referenced by arabicnumerals within parentheses. Full citations for these references may befound at the end of the specification immediately preceding the claims.The disclosures of these publications in their entireties are herebyexpressly incorporated by reference into this application.

In the area of coating systems utilizing metal pigment particles,aqueous systems present rather formidable difficulties. This isparticularly true with respect to aluminum and zinc pigments. Thus, themetal pigment can readily react with water to generate hydrogen gas. Theamount of gas generated can produce a safety hazard, creating highpressures within the composition containers. Also, the water reactionsubstantially diminishes the aesthetic value of metal pigments. Thereaction of aluminum pigments with water can be depicted as follows:

    2Al+6H.sub.2 O==2Al(OH).sub.3 +3H.sub.2 (g)

Due to the increasing demand for aqueous systems, a number of techniqueshave been proposed for inhibiting the attack on the pigment particles bywater. Unfortunately, most of these techniques have not providedsufficient protection.

One technique that provides inhibiting properties is the passivation ofthe metal pigment particles with an ionic organic phosphate as disclosedby Williams et al., U.S. Pat. No. 4,565,716, the disclosure of which isincorporated herein by reference. Another technique involves the use ofcompounds containing hexavalent chromium or pentavalent vanadiumcompounds as disclosed in Kondis U.S. Pat. No. 4,693,754, the disclosureof which is incorporated herein by reference. Other techniques includethe use of organic phosphites as disclosed in Kondis et al. U.S. Pat.No. 4,808,231, the disclosure of which is incorporated herein byreference, or the use of nitroparaffin solvents. Still another techniqueincludes the use of either (a) an ionic organic phosphate compound, forexample as taught in Williams et al., U.S. Pat. No. 4,565,716, or (b) apentavalent vanadium compound, for example as taught in Kondis, U.S.Pat. No. 4,693,754, or (c) an organic phosphite compound, for example astaught in Kondis et al. U.S. Pat. No. 4,808,231, in combination with anitro-containing solvent such as a nitroparaffin as disclosed in Keemeret al., U.S. Pat. No. 5,215,579, the disclosure of which is incorporatedherein by reference.

The treated metal pigment particles can be used to form a metal pigmentpaste. The treatment produces a metal pigment paste which has improvedgassing stability over conventionally treated products.

SUMMARY OF THE INVENTION

The present invention is directed to metal particles which have beentreated with (1) at least one heteropoly anion, (2) at least onephosphosilicate pigment or (3) a combination of at least one heteropolyanion and at least one phosphosilicate pigment. The metal particles,(e.g. aluminum flakes), which have been treated in this manner arestabilized to a degree suitable for use in aqueous coating systems.

A principle object of the invention is to provide a metal flake whichcan be used in aqueous systems and which is resistant to hydrogenevolution.

Another object of the invention is to provide a metal flake whichmaintains acceptable aesthetic values and intercoat and intracoatadhesion in the paint film.

Other objects, advantages and features of the present invention will bemore readily appreciated and understood when considered in conjunctionwith the following detailed description.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

All the disclosed embodiments can be made using conventional compoundsand procedures without undue experimentation.

As indicated above, the present invention is based on the discovery thatcertain types of heteropoly anion compounds, certain types ofphosphosilicate compounds, or a combination thereof, effectivelystabilize metal pigments from reacting with water, rendering the metalpigment suitable for use in water-based coatings without significantevolution of hydrogen without loss of adhesion, or degradation ofoptical properties. The present invention is especially useful for zinc,aluminum and bronze pigments.

Heteropoly anions are polymeric oxoanions which are formed by theacidification of solutions containing the requisite simple anions or byintroduction of the hetero element ion after first acidifying themolybdate or tungstate anions. Heteropoly anions are described in Table22C-2, at page 857 of Advanced Inorganic Chemistry by Cotton andWilkenson.sup.(1), the entire disclosure of which is incorporated hereinby reference. The largest and best known group of heteropoly anions iscomposed of those with the hetero atom(s) enshrouded by a cage of MO₆octahedra. One of the most common structures of heteropoly anions is theKeggin structure which is represented by [X^(+n) M₁₂ O₄₀ ].sup.(8-n)-where M represents molybdenum or tungsten and X represents silicon,germanium, phosphorus, arsenic, titanium, zirconium, etc. Preferredheteropoly anion groups are the heteropoly molybdates and the heteropolytungstates. Preferred heteropoly anion compounds are silicomolybdic acid(SiMoA), phosphotungstic acid (PWA) and silicotungstic acid (SiWA). Anespecially preferred compound is phosphomolybdic acid (PMoA). Theconcentration of the heteropoly anion compound should be from 0.1% to30%, preferably from 1% to 10%, based on the metal particle weight.

Phosphosilicate pigments contain phosphorous, silicon and oxygen.Examples of phosphosilicate pigment compounds are calciumphosphosilicate, calcium strontium phosphosilicate and aluminumzirconium zinc phosphosilicate. An especially preferred compound iscalcium strontium zinc phosphosilicate marketed by Halox Pigments ofHammond, Indiana, under the tradename of Halox SZP391. The amount of thephosphosilicate compound should be from 0.1% to 30%, preferably 10%,based on the metal particle weight.

Solvents for use with the heteropoly anions may include glycol ethers,glycol ether acetates, alcohols, water and nitroparaffins, or any othersolvent compatible with coating systems, in which the heteropoly anionis soluble. Among the nitroparaffins for use with heteropoly anions, thelower members of the nitroparaffin series, i.e., nitromethane,nitroethane and 1-nitropropane, are preferred on the basis oftoxicological properties and availability. The solvent for use withheteropoly anions should be present at 5% to 100%, but preferably 20% ormore, most preferably 35% or more, of the total weight of solvent in thefinal metal pigment paste. The solvent for use with heteropoly anions isgenerally about 28% to 50% by weight of the paste. The heteropoly anionsolvent may also include surface active agents such as surfactants oranti-foaming agents.

Solvents for use with the phosphosilicate pigments may include mineralspirits, high-flash naphtha, glycol ethers, glycol ether acetates,nitroparaffins, alcohols, acetates, or any other solvent compatible withcoating systems. The solvent may optionally include surface activeagents such as surfactants, anti-foaming agents and dispersants. Amongthe nitroparaffins for use with phosphosilicate pigments, the lowermembers of the nitroparaffin series, (i.e., nitromethane, nitroethaneand 1-nitropropane), are preferred on the basis of toxicologicalproperties and availability. The solvent for use with thephosphosilicate pigments should be present in an amount of from 5% to100%, but preferably 20% or more, most preferably 35% or more, based onthe total weight of solvent in the final metal pigment paste.

Solvents for use with the combination of heteropoly anions andphosphosilicate pigments may include glycol ethers, glycol etheracetates, alcohols, water and nitroparaffins, or any other solventcompatible with coating systems, in which the heteropoly anion issoluble. Among the nitroparaffins, the lower members of thenitroparaffin series, i.e., nitromethane, nitroethane and1-nitropropane, are preferred on the basis of toxicological propertiesand availability. The solvent for use with heteropoly anions andphosphosilicate pigments should be present at 5% to 100%, but preferably20% or more, most preferably 35% or more, of the total weight of solventin the final metal pigment paste. The solvent may also include surfaceactive agents such as surfactants or anti-foaming agents.

A preferred method to incorporate the heteropoly anion compound is avariation of the slurry method taught in Kondis U.S. Pat. No. 4,693,754.A metal pigment particle filter cake or paste, typically containing 50%to 95%, preferably 60% to 85%, of metal pigment in a solvent, is addedto a mixture composed of 15% to 94.5%, preferably 65% to 89%, of asolvent in which the heteropoly anion is soluble. The desired amount ofthe heteropoly anion compound, typically 0.1 to 30%, preferably 1.0-10%,based on the weight of the metal particles, is added to form a reactionmixture. Surfactants, dispersants, anti-foaming agents, etc., may alsobe added to the reaction mixture. The reaction mixture is agitated at atemperature of from 20° C. to 100° C., preferably ambient to 80° C., fora period of time ranging from 0.5 to 30 hours, preferably 2 to 8 hours.Solvent is then removed to obtain the desired final metal pigmentparticle content, typically 40% to 90%.

A preferred method to incorporate the phosphosilicate pigment also is toincorporate the phosphosilicate pigment compound by a variation of theslurry method taught in Kondis U.S. Pat. No. 4,693,754. A metal pigmentparticle filter cake or paste, typically containing 50% to 95%,preferably 60% to 85%, of metal pigment in a solvent, is added to amixture composed of 15% to 94.5%, preferably 65% to 89%, of a solvent inwhich the phosphosilicate pigment is dispersable. The desired amount ofthe phosphosilicate pigment compound, typically 0.1 to 30%, preferably10%, based on the weight of the metal particles, is added to form areaction mixture. The phosphosilicate pigment may first be dispersed ina solvent. Surfactants, dispersants, anti-foaming agents, etc., may alsobe added to the reaction mixture. The reaction mixture is agitated at atemperature of 20° C. to 100° C., preferably ambient to 80° C., for aperiod of time ranging from 5 minutes to 24 hours, preferably 1/2 to 2hours. Solvent is then removed to obtain the desired final metal pigmentparticle content, typically 40% to 90%.

Likewise, a preferred method to incorporate both the heteropoly anioncompound and the phosphosilicate pigment is the variation of the slurrymethod taught in Kondis U.S. Pat. No. 4,693,754. A metal pigmentparticle filter cake or paste, typically containing 50% to 95%,preferably 60% to 85%, of metal pigment in a solvent, is added to amixture composed of 15% to 94.5%, preferably 65% to 89%, of a solvent inwhich the heteropoly anion is soluble. The desired amount of theheteropoly anion compound, typically 0.1 to 30%, preferably 0.2-10%,based on the weight of the metal particles and the desired amount of thephosphosilicate pigment, typically 0.1% to 30%, preferably 1% to 10%,based on the weight of the metal particles, is added to form a reactionmixture. Surfactants, dispersants, anti-foaming agents, etc., may alsobe added to the reaction mixture. The reaction mixture is agitated at atemperature of from 20° C. to 100° C., preferably ambient to 80° C., fora period of time ranging from 0.5 to 30 hours, preferably 2 to 8 hours.Solvent is then removed to obtain the desired final metal pigmentparticle content, typically 40% to 90%.

In addition to the treatment methods described above, another techniqueis to introduce the heteropoly anion compound, phosphosilicate compoundor the combination thereof into a ball mill, along with atomized powderor foil, lubricants and solvents etc. used to produce aluminum pigments.Thus, the metal pigment surfaces are stabilized as they are beinggenerated in the ball mill.

The preferred treatment processes provide excellent stability,regardless of the lubricant used in milling.

The pigment paste obtained can be used in a variety of known coatingsystems, as a direct replacement for currently used pastes. Examplesinclude maintenance, general industrial, roof coating, and automotivecoating systems. Thus, the paste may be used, for example, with acrylicpolymer emulsions, water reducible alkyd resin systems, water reduciblealkyd/melamine cross-linked systems, waterborne epoxy coatings,polyester emulsions and water reducible polyester melamine coatings.

It is also possible to treat the metal particles after they have beencombined with an aqueous coating vehicle. Thus, the heteropolyanion,phosphosilicate or the combination thereof can be added to an aqueouscarrier itself either before or after the metal particles have beenadded to the coating composition. If the heteropolyanion compound,phosphosilicate compound or combination is added after the metalparticles are added, the delay should not be long, since a long delaywould permit the aqueous carrier to attack the metal particles. In thecase where the addition is made to the coating composition, the amountsof heteropolyanion, phosphosilicate or combination thereof can be thesame as discussed above for producing treated metal particles in pasteform. Simple mixing techniques can be employed.

The treatment with heteropolyanion, phosphosilicate or both can becombined with other treatment methods, including the use ofnitroparaffins, ionic organic phosphates, organic phosphites, andvanadium compounds. The other treatment methods can be carried outbefore, during or after the treatment with heteropoly anion,phosphosilicate or both.

EXAMPLES

Specific embodiments of the invention will now be further described bythe following, non-limiting examples.

EXAMPLE 1

124.3 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843(non-volatile 70.8%) is slurried with 514 grams of glycol ether PM toyield a slurry concentration of 13.8% aluminum. To this slurry 10% byweight phosphomolybdic acid is added, based on the weight of aluminum inthe paste feed. The material is agitated for 5 hours, at 80° C. Theslurry is then filter pressed to obtain a finished paste of 64%non-volatile content and then tested for aqueous stability as describedbelow.

EXAMPLE 2

124.3 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843 isslurried with 514 grams of glycol ether PM to yield a slurryconcentration of 13.8% aluminum. To this slurry 10% by weightsilicomolybdic acid is added, based on the weight of aluminum paste inthe feed. The material is agitated for 5 hours, at 80° C. The slurry isthen filter pressed to obtain a finished paste of 69.2% non-volatilecontent and then tested for aqueous stability as described below.

EXAMPLE 3

124.3 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843 isslurried with 514 grams of glycol ether PM to yield a slurryconcentration of 13.8% aluminum. To this slurry 10% by weightphosphotungstic acid is added, based on the weight of aluminum in thepaste feed. The material is agitated for 5 hours, at 80° C. The slurryis then filter pressed to obtain a finished paste of 65.2% non-volatilecontent and then tested for aqueous stability as described below.

COMPARATIVE EXAMPLE 1

130 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843 isslurried with 443 grams of glycol ether PM to yield a slurryconcentration of 16.1% aluminum. In order to provide a comparativeexample, no heteropoly anion is added to this slurry. The slurry is thenfilter pressed to obtain a finished paste of 70% non-volatile contentand then tested for aqueous stability as described below.

Each of the finished pastes obtained from the above examples isincorporated into a typical aqueous general industrial coatingformulation prepared according to the following procedure. Enough ofeach paste to yield 20.5 g of aluminum is weighed out. The paste, 41.2 gglycol ether EB, 5.1 g Texanol (supplier--Eastman), 1.03 g Patcote 519(supplier--Patcote), 0.62 g Dow Corning 14 (supplier--Dow), 73.5 gdeionized water, and 313.7 g Joncryl 537 Resin, an acrylic emulsion(supplier--Johnson Wax) are blended together to form a uniform coating.

The formulations are placed in a constant temperature bath at 52° C. andthe gas evolved is collected in an inverted water-filled buret for 168hours. The data are summarized in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    ALUMINUM PASTE                    GASSING                                     FEED         REAGENT AMOUNT                                                                              PROCESS                                                                              (mls.)                                      __________________________________________________________________________    Example 1-   Phosphomoly-                                                                          10%   5 hrs. 80° C.                                                                  37                                         TIFFLAKE ™ 5843                                                                         bdic Acid                                                        Example 2-   Silicomolybdic                                                                        10%   5 hrs. 80° C.                                                                  70                                         TIFFLAKE ™ 5843                                                                         Acid                                                             Example 3-   Phosphotungstic                                                                       10%   5 hrs. 80° C.                                                                 146                                         TUFFLAKE ™ 5843                                                                         Acid                                                             Comparative Example 1                                                                      None    0     --     181                                         __________________________________________________________________________

The results clearly show that the use of a heteropoly anion as aninhibitor reduces undesirable gassing and that the type of heteropolyanion used affects the amount of observed gassing.

The finished aluminum paste of Example 1 was incorporated into anaqueous automotive basecoat formulation. The formulation obtained wassprayed onto electrocoated steel panels, and then clear coated with asolvent-borne automotive formulation. This panel was placed in anenclosed chamber maintained at 100° F. (38° C.) and 100% relativehumidity, in accordance with ASTM D2247-87. After 10 days of exposure,the panel was removed from the chamber and dried. No blistering orvisual degradation was noted. The panel was then tested for adhesion, inaccordance with ASTM D3359-87, Test Method B. No loss of adhesionoccurred.

EXAMPLE 4

112.2 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-AR(non-volatile of 78.1%) is slurried with 531.4 grams of glycol ether PMto yield a slurry concentration of 13.6% aluminum. To this slurry 1.6%by weight phosphomolybdic acid is added, based on the weight of aluminumin the paste feed. The material is agitated for two hours, at 80° C. Theslurry is then filter pressed to obtain a finished paste of 66%non-volatile content and then tested for aqueous stability as describedbelow.

EXAMPLE 5

41.3 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 602.4 grams of glycol ether PM to yield a slurryconcentration of 5.0% aluminum. To this slurry 4.0% by weightphosphomolybdic acid is added, based on the weight of aluminum in thepaste feed. The material is agitated for five hours, at 80° C. Theslurry is then filter pressed to obtain a finished paste of 68.1%non-volatile content and then tested for aqueous stability as describedbelow.

EXAMPLE 6

76.8 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 562.2 grams of glycol ether PM to yield a slurryconcentration of 9.4% aluminum. To this slurry 10.0% by weightphosphomolybdic acid is added, based on the weight of aluminum in thepaste feed. The material is agitated for 0.5 hours, at 80° C. The slurryis then filter pressed to obtain a finished paste of 68.8% non-volatilecontent and then tested for aqueous stability as described below.

EXAMPLE 7

41.3 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 600.5 grams of glycol ether PM to yield a slurryconcentration of 5.0% aluminum. To this slurry 10.0% by weightphosphomolybdic acid is added, based on the weight of aluminum in thepaste feed. The material is agitated for 2 hours, at 55° C. The slurryis then filter pressed to obtain a finished paste of 68.2% non-volatilecontent and then tested for aqueous stability as described below.

EXAMPLE 8

112.2 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 524 grams of glycol ether PM to yield a slurryconcentration of 13.8% aluminum. To this slurry 10.0% by weightphosphomolybdic acid is added, based on the weight of aluminum in thepaste feed. The material is agitated for 5 hours, at 30° C. The slurryis then filter pressed to obtain a finished paste of 65.2% non-volatilecontent and then tested for aqueous stability as described below.

COMPARATIVE EXAMPLE 2

112.7 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 474 grams of glycol ether PM to yield a slurryconcentration of 15% aluminum. In order to provide a comparativeexample, no heteropoly anion is added to this slurry. The slurry is thenfilter pressed to obtain a finished paste of 70% non-volatile contentand then tested for aqueous stability as described below.

Each of the finished aluminum pastes obtained from the above examples isincorporated into a general industrial aqueous coating formulation. Theformulations are placed in a constant temperature bath at 52° C., andthe gas evolved is collected in an inverted water-filled buret for 168hours. The data are summarized in Table 2.

                                      TABLE 2                                     __________________________________________________________________________    EXPERIMENTAL CONDITIONS                                                       ALUMINUM PASTE                                                                            AMOUNT                                                                              TIME                                                                              TEMPERA-                                                                             SLURRY                                                                              GASSING                                    FEED        PMoA  (Hrs.)                                                                            TURE   CONC. (mls.)                                     __________________________________________________________________________    Example 4-SPARKLE                                                                          1.6% 2   80° C.                                                                        13.6% Al                                                                             50.2                                      SILVER ® 5245-AR                                                          Example 5-SPARKLE                                                                          4.0% 5   80° C.                                                                         5.0% Al                                                                             32.0                                      SILVER ® 5245-AR                                                          Example 6-SPARKLE                                                                         10.0% 0.5 80° C.                                                                         9.3% Al                                                                             48.4                                      SILVER ® 5245-AR                                                          Example 7-SPARKLE                                                                         10.0% 2   55° C.                                                                         5.0% Al                                                                             39.4                                      SILVER ® 5245-AR                                                          Example 8-SPARKLE                                                                         10.0% 5   30° C.                                                                        13.6% Al                                                                             36.1                                      SILVER ® 5245-AR                                                          Comparative Example 2                                                                     None  --  --       15% Al                                                                            193.3                                      __________________________________________________________________________

The data clearly shows that the use of a heteropoly anion reduces theamount of undesirable gassing compared to an untreated sample.

EXAMPLE 9

112 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-AR(Non-Volatile 78.2%), is slurried with 464.0 grams of mineral spirits toyield a slurry concentration of 15.2% aluminum. To this slurry 10% byweight calcium strontium zinc phosphosilicate is added, based on theweight of aluminum in the paste feed. The material is agitated for fivehours, at 30° C. The slurry is then filter pressed to obtain a finishedpaste of 72.6% non-volatile content and then tested for aqueousstability as described below.

COMPARATIVE EXAMPLE 3

137 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 447 grams of mineral spirits to yield a slurryconcentration of 15% aluminum. In order to provide a comparativeexample, no calcium strontium zinc phosphosilicate is added to thisslurry. The slurry is then filter pressed to obtain a finished paste of64% non-volatile content and then tested for aqueous stability asdescribed below.

Each of the finished pastes obtained from the above examples isincorporated into a typical aqueous general industrial coatingformulation prepared according to the following procedure. Enough ofeach paste to yield 20.5 g of aluminum is weighed out. The paste, 41.2 gglycol ether EB, 5.1 g Texanol (supplier--Eastman), 1.03 g Patcote 519(supplier--Patcote), 0.62 g Dow Corning 14 (supplier--Dow), 73.5 gdeionized water, and 313.7 g Joncryl 537 Resin, an acrylic emulsion(supplier--Johnson Wax) are blended together to form a uniform coating.

The coating formulations are placed in a constant temperature bath at52° C. and the gas evolved is collected in an inverted water-filledburst for 168 hours. The data are summarized in Table 3.

                  TABLE 3                                                         ______________________________________                                                             GASSING                                                  ALUMINUM PASTE FEED  (mls.)                                                   ______________________________________                                        Example 9-SPARKLE     14.95                                                   SILVER ® 5245-AR                                                          Comparative Example 3                                                                              193.30                                                   ______________________________________                                    

The data clearly show that the use of calcium strontium zincphosphosilicate as an inhibitory pigment reduces undesirable gassing bymore than an order of magnitude compared to untreated samples.

EXAMPLE 10

76.8 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 502.2 grams of mineral spirits to yield a slurryconcentration of 10.4% aluminum. To this slurry 1.6% by weight calciumstrontium zinc phosphosilicate is added, based on the weight of aluminumpaste in the feed. The material is agitated for 5 hours, at 55° C. Theslurry is then filter pressed to obtain a finished paste of 76%non-volatile content and then tested for aqueous stability as describedbelow.

EXAMPLE 11

41.6 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5245-ARis slurried with 540.5 grams of mineral spirits to yield a slurryconcentration of 5.5% aluminum. To this slurry 4.0% by weight calciumstrontium zinc phosphosilicate is added, based on the weight of aluminumpaste in the feed. The material is agitated for 5 hours, at 80° C. Theslurry is then filter pressed to obtain a finished paste of 76%non-volatile content and then tested for aqueous stability as describedbelow.

EXAMPLE 12

124.3 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843(Non-Volatile 70.8%) is slurried with 429 grams of mineral spirits toyield a slurry concentration of 15.9% aluminum. To this slurry 10% byweight calcium strontium zinc phosphosilicate is added, based on theweight of aluminum in the paste feed. The material is agitated for onehour, at ambient temperature. The slurry is then filter pressed toobtain a finished paste of 73.2% non-volatile content and then testedfor aqueous stability as described below.

EXAMPLE 13

124.3 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843 isslurried with 429 grams of mineral spirits to yield a slurryconcentration of 15.9% aluminum. To this slurry 15% by weight calciumstrontium zinc phosphosilicate is added, based on the weight of aluminumin the paste feed. The material is agitated for one hour, at ambienttemperature. The slurry is then filter pressed to obtain a finishedpaste of 70.7% non-volatile content and then tested for aqueousstability as described below.

EXAMPLE 14

124.3 grams of a non-leafing aluminum paste feed TUFFLAKE® 5843 isslurried with 429 grams of mineral spirits to yield a slurryconcentration of 15.9%. To this slurry 20% by weight calcium strontiumzinc phosphosilicate is added, based on the weight of aluminum in thepaste feed. The material is agitated for one hour, at ambienttemperature. The slurry is then filter pressed to obtain a finishedpaste of 69.2% non-volatile content and then tested for aqueousstability as described below.

The finished aluminum pastes obtained from the above examples areincorporated into general industrial aqueous coating formulations. Theformulations are placed in a constant temperature bath at 52° C., andthe gas evolved is collected in an inverted water-filled buret for 168hours. The data is summarized in Table 4.

                                      TABLE 4                                     __________________________________________________________________________    EXPERIMENTAL CONDITIONS                                                       ALUMINUM PASTE                                                                             AMOUNT                                                                              TIME                                                                              TEMPERA-                                                                             SLURRY                                                                              GASSING                                   FEED         PMoA  (Hrs.)                                                                            TURE   CONC. (mls.)                                    __________________________________________________________________________    Example 10-SPARKLE                                                                          1.6% 5   55° C.                                                                        10.4% Al                                                                            182.15                                    SILVER ® 5245-AR                                                          Example 11-SPARKLE                                                                          4.0% 5   80° C.                                                                         5.5% Al                                                                            128.15                                    SILVER ® 5245-AR                                                          Example 9-SPARKLE                                                                          10.0% 5   30° C.                                                                        15.2% Al                                                                            14.95                                     SILVER ® 5245-AR                                                          Example 12-  10.0% 1   Ambient                                                                              15.9% Al                                                                             9.40                                     TUFFLAKE ™ 5843                                                            Example 13-  15.0% 1   Ambient                                                                              15.9% Al                                                                             4.80                                     TIFFLAKE ™ 5843                                                            Example 14-  20.0% 1   Ambient                                                                              15.9% Al                                                                             6.70                                     TUFFLAKE ™ 5843                                                            __________________________________________________________________________

The data clearly shows that different amounts of calcium strontium zincphosphosilicate affect the amount of undesirable gassing. It can also beseen that the processing variables of time and temperature affect thelevel of undesirable gassing.

Each of the finished aluminum pastes of Examples 9 and 12 wasincorporated into an aqueous automotive basecoat formulation. Theformulations obtained were sprayed onto electrocoated steel panels, andthen clear coated with a solvent-borne automotive formulation. Thesepanels were placed in an enclosed chamber maintained at 100° F. (38° C.)and 100% relative humidity, in accordance with ASTM D2247-87. After 10days of exposure, the panels were removed from the chamber and dried. Noblistering or visual degradation was noted. The panels were then testedfor adhesion, in accordance with ASTM D3359-87, Test Method B. No lossof adhesion occurred.

EXAMPLE 15

139.1 grams of a non-leafing aluminum paste feed SPARKLE SILVER® 5745ALUMINUM PASTE (non-volatile 64.7%) is slurried in 513.7 grams of glycolether PM. To this slurry 2.78% by weight phosphomolybdic acid and 10% byweight calcium strontium zinc phosphosilicate is added, based on theweight of aluminum in the paste feed. The material is agitated for five(5) hours, at 80° C. The slurry is then filter pressed to obtain afinished paste product and then tested for aqueous stability asdescribed below.

EXAMPLES 16-27 AND COMPARATIVE EXAMPLES 4-7

The procedure of Example 15 is repeated, varying the amounts ofphosphomolybdic acid and calcium strontium zinc phosphosilicate. For thecomparative examples, only one of the reagents is used. The formulationsare detailed in Table 5.

Each of the finished pastes obtained from the above examples isincorporated into a typical aqueous general industrial coatingformulation prepared according to the following procedure. Enough ofeach paste to yield 20.5 g of aluminum is weighed out. The paste, 41.2 gglycol ether EB, 5.1 g Texanol (supplier--Eastman), 1.03 g Patcote 519(supplier--Patcote), 0.62 g Dow Corning 14 (supplier--Dow), 73.5 gdeionized water, and 313.7 g Joncryl 537 Resin, an acrylic emulsion(supplier--Johnson Wax) are blended together to form a uniform coating.

The formulations are placed in a constant temperature bath at 52^(A) Cand the gas evolved is collected in an inverted water-filled buret for168 hours. The data are summarized in Table 5.

Some of the finished pastes obtained from the above examples are alsoincorporated into a proprietary aqueous automotive base coatformulation. The formulations are placed in a constant temperature bathat 52^(A) C and the gas evolved is collected in an inverted water-filledburet for 168 hours. The data are summarized in Table 5.

Several of these aqueous automotive base coat formulations were sprayedonto electrocoated steel panels, and then clear coated with asolvent-borne automotive formulation. These panels were placed in anenclosed chamber maintained at 100° F. (38° C.) and 100% relativehumidity, in accordance with ASTM D2247-87. After 10 days of exposure,the panels were removed from the chamber, dried, and inspected forblistering or visual degradation. The panels were then tested foradhesion, in accordance with ASTM D3359-87, Test Method B. The data aresummarized in Table 5.

                                      TABLE 5                                     __________________________________________________________________________                CALCIUM                                                           PHOSPHO-    STRONTIUM          GENERAL AUTO-                                  MOLYBDIC    ZINC        TOTAL  INDUSTRIAL                                                                            MOTIVE                                 ACID, %     PHOSPHOSILICATE                                                                           INHIBITOR                                                                            GASSING GASSING                                                                             HUMIDITY RESISTANCE              ON AL       % ON ALUMINUM                                                                             % ON AL                                                                              (mls)   (mls) AESTHETICS                                                                            ADHESION                 __________________________________________________________________________                                                         LOSS                     EX.                                                                            1   2.78   10.0        12.78  0       0.4   N/T     N/T                       2   4.0    7.5         11.5   1.7     N/T   N/T     N/T                       3   1.25   10.0        11.25  0.3     0     Good    0                         4   0.75   10.0        10.75  0.3     N/T   N/T     N/T                       5   0.2    10.0        10.2   3.5     0     Good    0                         6   2.5    7.5         10.0   0.85    0     Good    0                         7   5.0    5.0         10.0   3.85    0     Good    0                         8   7.5    2.5         10.0   7.6     0     N/T     N/T                       9   1.0    8.4         9.4    4.5     N/T   N/T     N/T                      10   1.0    7.5         8.5    3.45    N/T   N/T     N/T                      11   3.5    3.5         7.0    16.25   0     N/T     N/T                      12   1.0    5.0         6.0    14.90   N/T   N/T     N/T                      13   1.25   1.25        2.5    28.65   0     N/T     N/T                      COMP.                                                                         EX.                                                                            1   10.0   0           10.0   45.05   0     Good    0                         2   5.0    0           5.0    78.5    N/T   N/T     N/T                       3   0      10.0        10.0   25.05   12.55 Good    0                         4   0      4.0         4.0    127.7   N/T   N/T     N/T                      __________________________________________________________________________     N/T = NOT TESTED                                                         

EXAMPLE 28

Untreated SS-5745 was incorporated into a typical aqueous genealindustrial formulation prepared according to the following procedure.Enough paste to yield 20.5 g. of aluminum is weighed out. The paste,41.2 g. of Glycol Ether EB, 5.1 g. Texanol (Supplier: Eastman Chemical),73.5 g. deionized water, and 313.7 g. Joncryl 537 resin, an acrylicemulsion (Supplier: Johnson Wax) were blended together to form a uniformcoating.

The paints were then treated insitu with calcium strontium zincphosphosilicate at levels of 0%, 5%, 10%, and 15% on metal weight in theformulation. The paints were then subjected to the gassing test (asdescribed previously) and the results are shown in Table 6.

                  TABLE 6                                                         ______________________________________                                                   Calcium Strontium Zinc                                                        Phosphosilicate % on                                               Paint      Aluminum Insitu Treatment                                                                        Gassing (mls)                                   ______________________________________                                        SS-5745/Joncryl                                                               537 Paint   0                 143.00                                                      5                 43.3                                                       10                 17.25                                                      15                 17.35                                           ______________________________________                                    

As can be seen from the table, the insitu addition improves the gassingstability over untreated paints.

In the general industrial formulation, all the combinations, ofheteropoly anion and phosphosilicate compound yield lower gassing thanthe heteropoly anion compound, alone, or the phosphosilicate compoundalone, at the 4% level; and all but one are lower than thephosphosilicate compound, alone, at the 10% level. In the automotiveformulation, all the combinations of heteropoly anion andphosphosilicate compound, yield lower gassing than the phosphosilicatecompound, alone, and are equivalent to the heteropoly anion compound,alone. All provide good aesthetics and no adhesion loss in the humiditytest.

While there is shown and described herein certain specific examplesembodying this invention for the purpose of clarity of understanding,the same is to be considered as illustrative in character, it beingunderstood that only preferred embodiments have been shown anddescribed. It will be manifest to those skilled in the art that certainchanges, various modifications and rearrangements of the parts may bemade without departing from the spirit and scope of the underlyinginventive concept and that the same is not limited to the particularforms herein shown and described except insofar as indicated in thescope of the appended claims.

The entirety of everything cited above or below is expresslyincorporated herein by reference.

REFERENCES

1. Cotton, F. Albert, and Wilkinson, Geoffrey, Advanced InorganicChemistry, 4th Ed., published by Wiley-Interscience.

What is claimed is:
 1. A metal pigment-containing paste suitable forformation of a coating composition, comprising:metal pigment particles;a solvent; and a treating agent for the metal pigment particles selectedfrom the group consisting of at least one heteropolyanion compound, atleast one phosphosilicate compound, and a combination of at least oneheteropolyanion and at least one phosphosilicate compound.
 2. The metalpigment-containing paste of claim 1, wherein the metal pigment particlescomprise aluminum.
 3. The metal pigment-containing paste of claim 1,wherein the metal pigment particles comprise zinc.
 4. The metalpigment-containing paste of claim 1, wherein the metal pigment particlescomprise bronze.
 5. The metal pigment-containing paste of claim 1,wherein the metal pigment particles are present in an amount of fromapproximately 40% to approximately 90% by weight of the paste.
 6. Themetal pigment-containing paste of claim 1, wherein the heteropoly anionis present in an amount of from approximately 0.1% to approximately30.0% by weight of the metal pigment particles.
 7. The metalpigment-containing paste of claim 6, wherein the amount ofheteropolyanion compound is from approximately 1.0% to approximately 10%by weight of the metal pigment particles.
 8. The metalpigment-containing paste of claim 1, wherein the heteropolyanioncompound is present and the solvent comprises at least one memberselected from the group consisting of glycol ethers, glycol etheracetates, alcohols, water and nitroparaffins.
 9. The metalpigment-containing paste of claim 1, wherein the heteropolyanioncompound is present and comprises at least one member selected from thegroup consisting of silicomolybdic acid, phosphotungstic acid,silicotungstic acid and phosphomolybdic acid.
 10. The metalpigment-containing paste of claim 9, wherein the heteropoly anioncomprises phosphomolybdic acid.
 11. The metal pigment-containing pasteof claim 1, wherein the solvent further comprises a surface activeagent.
 12. The metal pigment-containing paste of claim 1, wherein thephosphosilicate compound is present in an amount of from approximately0.1% to approximately 30.0% by weight of the metal pigment particles.13. The metal pigment-containing paste of claim 12, wherein the amountof phosphosilicate compound is approximately 10% by weight of the metalpigment particles.
 14. The metal pigment-containing paste of claim 12,wherein the phosphosilicate compound is present and the solventcomprises at least one member selected from the group consisting ofmineral spirits, high flash naphtha, glycol ethers, glycol etheracetates, nitroparaffins, alcohols and acetates.
 15. The metalpigment-containing paste of claim 12, wherein the phosphosilicatecompound comprises at least one member selected from the groupconsisting of calcium phosphosilicate, calcium strontiumphosphosilicate, aluminum zirconium zinc phosphosilicate and calciumstrontium zinc phosphosilicate.
 16. The metal pigment-containing pasteof claim 15, wherein the phosphosilicate compound comprises calciumstrontium zinc phosphosilicate.
 17. The metal pigment-containing pasteof claim 14, wherein the solvent further comprises a surface activeagent.
 18. The metal pigment-containing paste of claim 1, wherein acombination of heteropolyanion compound and phosphosilicate compound ispresent.
 19. The metal pigment-containing paste of claim 18, wherein theheteropolyanion compound is present in an amount of from approximately0.1% to approximately 30.0% by weight of the metal pigment particles.20. The metal pigment-containing paste of claim 19, wherein the amountof heteropolyanion compound is from approximately 0.2% to approximately10% by weight of the metal pigment particles.
 21. The metalpigment-containing paste of claim 18, wherein the phosphosilicatecompound is present in an amount of from approximately 0.1% toapproximately 30.0% by weight of the metal pigment particles.
 22. Themetal pigment-containing paste of claim 21, wherein the amount ofphosphosilicate compound is from approximately 1.0% to approximately 10%by weight of the metal pigment particles.
 23. The metalpigment-containing paste of claim 18, wherein the solvent comprises atleast one member selected from the group consisting of glycol ethers,glycol ether acetates, alcohols, water and nitroparaffins.
 24. The metalpigment-containing paste of claim 18, wherein the heteropolyanioncompound comprises at least one member selected from the groupconsisting of silicomolybdic acid, phosphotungstic acid, silicotungsticacid and phosphomolybdic acid.
 25. The metal pigment-containing paste ofclaim 24, wherein the heteropoly anion comprises phosphomolybdic acid.26. The metal pigment-containing paste of claim 18, wherein thephosphosilicate compound comprises at least one member selected from thegroup consisting of calcium phosphosilicate, calcium strontiumphosphosilicate, aluminum zirconium zinc phosphosilicate and calciumstrontium zinc phosphosilicate.
 27. The metal pigment-containing pasteof claim 26, wherein the phosphosilicate compound comprises calciumstrontium zinc phosphosilicate.
 28. The metal pigment-containing pasteof claim 18, wherein the solvent further comprises a surface activeagent.
 29. An aqueous coating composition comprising:a metalpigment-containing paste as claimed in claim 1; and an aqueous carrier.30. A method of making a metal pigment-containing paste useful forforming a coating composition, comprising:(a) producing metal particles;and (b) contacting the metal particles with at least one heteropolyanioncompound, at least one phosphosilicate compound or a combination ofleast one heteropolyanion compound and at least one phosphosilicatecompound.
 31. A coating composition comprising the metalpigment-containing paste made according to the method of claim
 30. 32.In a painted automobile, the improvement comprising paint containingmetal particles which have been treated with at least oneheteropolyanion compound, at least one phosphosilicate compound or acombination of at least one heteropolyanion compound and at least onephosphosilicate compound.
 33. A coating composition, comprising:metalpigment particles; an aqueous carrier; and a treating agent for themetal pigment particles selected from the group consisting of at leastone heteropolyanion compound, at least one phosphosilicate compound, anda combination of at least one heteropolyanion compound and at least onephosphosilicate compound.
 34. A method of making a coating composition,comprising:adding metal pigment particles to an aqueous carrier andadding a treating agent for the metal pigment particles selected fromthe group consisting of at least one heteropolyanion compound, at leastone phosphosilicate compound, and a combination of at least oneheteropolyanion and at least one phosphosilicate compound to the aqueouscarrier.
 35. A method of making a paint, comprising blending the metalpigment-containing paste of claim 1 with an aqueous carrier to form apaint.
 36. The method of claim 34, wherein the metal pigment particlesare added to the aqueous carrier prior to the treating agent.